Windows Dev Center

ISupportIncrementalLoading interface

Specifies a calling contract for collection views that support incremental loading.

Syntax


public interface class ISupportIncrementalLoading

Members

The ISupportIncrementalLoading interface has these types of members:

Methods

The ISupportIncrementalLoading interface has these methods. It also inherits methods from the Object class.

MethodDescription
LoadMoreItemsAsync Initializes incremental loading from the view.

 

Properties

The ISupportIncrementalLoading interface has these properties.

PropertyAccess typeDescription

HasMoreItems

Read-onlyGets a sentinel value that supports incremental loading implementations.

 

Examples

The following code example demonstrates how to implement this interface. For the complete code listing, see the XAML data Binding sample.


#pragma region Overridable methods

        virtual Concurrency::task<Windows::Foundation::Collections::IVector<Platform::Object^>^> LoadMoreItemsOverride(Concurrency::cancellation_token c, unsigned int count)
        {
            return Concurrency::task<Windows::Foundation::Collections::IVector<Platform::Object^>^>(
                [=]() -> Windows::Foundation::Collections::IVector<Platform::Object^>^ {
                    auto items = ref new Platform::Collections::Vector<Platform::Object^>();
                    return items;
            });
        }
        virtual bool HasMoreItemsOverride()
        {
            return false;
        }

#pragma endregion 

        IncrementalLoadingBase()
        {
            _storage = ref new Platform::Collections::Vector<Platform::Object^>();
            _storage->VectorChanged += ref new Windows::Foundation::Collections::VectorChangedEventHandler<Platform::Object^>(this, &IncrementalLoadingBase::_storageVectorChanged);
            _busy = false;
            _isVectorChangedObserved = false;
        }

    public:

        virtual Windows::Foundation::IAsyncOperation<Windows::UI::Xaml::Data::LoadMoreItemsResult>^ LoadMoreItemsAsync(unsigned int count)
        {
            if (_busy)
            {
                throw ref new Platform::FailureException("Only one operation in flight at a time");
            }

            _busy = true;

            return Concurrency::create_async([=](Concurrency::cancellation_token c) {
                return LoadMoreItemsAsync(c, count)
                    .then([=](Windows::UI::Xaml::Data::LoadMoreItemsResult result) -> Windows::UI::Xaml::Data::LoadMoreItemsResult {
                        _busy = false;
                        return result;
                });
            });
        }

        property bool HasMoreItems
        {
            virtual bool get() { return HasMoreItemsOverride(); }
        }

#pragma endregion 


Requirements (Windows 10 device family)

Device family

Universal

API contract

Windows.Foundation.UniversalApiContract, introduced version 1.0

Namespace

Windows.UI.Xaml.Data
Windows::UI::Xaml::Data [C++]

Metadata

Windows.Foundation.UniversalApiContract.winmd

Requirements (Windows 8.x and Windows Phone 8.x)

Minimum supported client

Windows 8

Minimum supported server

Windows Server 2012

Minimum supported phone

Windows Phone 8.1 [Windows Runtime apps only]

Namespace

Windows.UI.Xaml.Data
Windows::UI::Xaml::Data [C++]

Metadata

Windows.winmd

Attributes

[Version(0x06020000)]
[WebHostHidden()]

See also

Binding
XAML data Binding sample
Data binding overview

 

 

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